bio chapter 4

tissue

a group of cells with similar structure and function as well as similar extracellular substances located between the cells

histology

the study of tissue structure

epithelium or epithelial tissue

found throughout the body where it covers internal and external structures
-forms most glands; surfaces of the body include the outer layer of skin and lining of cavities such as digestive tract, respiratory tract, respiratory passages and blood vessels;

functions of epithelia

-protects underlying structures from abrasion
-prevents the movement of many substances through the epithelial layer
-allows the movement of many substances through the epithelial layer
-secrets substances from mucus glands sweat glands and the enzyme sec

number of cell layers and shape of cells

epithelia are classified according to ______________

simple epithelium

consists of a single layer of cells

stratified epithelium

consists of more than one layer of epithelial cells with some cells sitting on top of other cells

squamous

scale shape

cuboidal

cube like shape

columnar

tall and thin shape

simple epithelium

single layer of thin flat cells

simple squamous epithelium

-(structure)single layer of flat hexagonal cells, nuclei appear as bumps when viewed in cross section b/c cells are so flat
-(function) diffusion filtration some secretion and some protecting against friction
-(location) lining of blood vessels and the he

simple cuboidal epithelium

-(structure)single layer of cube shaped cells some cells have microvilli, or cilia
-(function)active transport and facilitated diffusion result in secretion and absorption by cells of the kidney tubules; secretion by cells of glands and choroid plexuses;

simple columnar epithelium

-(structure)single layer of tall narrow cells some cells have cilia or microvilli
-(function)movement of particles out of bronchioles of the lungs by ciliated cells; partially responsible for the movement of oocytes through the uterine tubes by ciliated c

pseudostratified columnar epithelium

-(structure)single layer of cells; some cells are tall and thin and reach the free surface others do not; the nuclei of these cells are at different levels and appear stratified; the cells are almost always ciliated and are associated with goblet cells th

stratified epithelium

several layers of cells

stratified squamous epithelium

-(structure)several layers of cells that are cuboidal in the basal layer and are progressively flattened towards the surface; can be nonkeratinized (moist) or keratinized; in non keratinized stratified squamous epithelium, the surface cells retain a nucle

stratified cuboidal epithelium

consists of more than one layer of cuboidal epithelia cells. this epithelial type is rare and is found in sweat glands ovarian follicular cells and salivary glands. functions are absorption secretion and protection

stratified columnar epithelium

consists of more than one layer of epithelial cells but only the serface cells are columnar in shape. the deeper layers are irregular in shape or cuboidal. this tissue type is also rare. it is found in locations such as the mammary glad ducts, the larynx,

transitional epithelium

a special type of epithelium that can be greatly stretched
-(structure)stratified cells that appear cuboidal when the organ or tube is not stretched and squamous when the organ or tube is stretched by fluid
-(function)accommodates fluctuations in the volu